1. Field of the Invention
The present invention relates to safety ski bindings in general and more specifically to an improved releasable and rotatable plate, turntable or pivot member associated with the heel hold-down device of the binding, wherein the plate or pivot member is rotatably mounted with the assistance of a mounting member rigid with the ski.
2. Description of the Prior Art
Among the hitherto known types of safety ski bindings there is a group of bindings comprising the so-called releasable plate, platform or turntable bindings and the so-called releasable pivot bindings. Regarding the turntable bindings, reference is made herein to those wherein the plate or turntable is disposed around a pivot member rigid with the ski and adapted to pivot in a plane parallel to the top surface of the ski. The purpose of these two types of bindings is to position the virtual fulcrum of the binding, during the release of the ski boot as a consequence of torsional stress, as close as possible to the axis of the skier's tibia and thus provide constant lever arms. Now, during actual skiing practice and notably when negotiating bumps, the ski is bent varying amounts and therefore either the ski boot sole or the plate is compressed undesirably between the safety members of the binding unless safety members are provided so that they can yield resiliently in the longitudinal direction of the ski.
To avoid this detrimental compression, a known solution consisted of providing an elongated hole through the plate surrounding or enclosing the pivot means rigid with the ski so that the plate could move in the longitudinal direction thereof. The plate then is resiliently urged and returned to its normal position at the end of the ski's bending movement by the safety means incorporated into the binding.
In the case of pivot bindings, it has already been proposed to prevent this undesired compression of the ski boot between the safety members when clearing bumps, by allowing the heel hold-down device to move against the resilient force of the safety mechanism towards the rear end of the ski and to be restored to its normal position by the safety mechanism.
Now these two prior art solutions are objectionable in that during normal ski bending movements that occur when skiing, the turntable or the heel hold-down device accomplishes a longitudinal movement which prestresses the mechanism controlling the release of the safety members, whereby either the release forces are increased or the release takes place untimely. These two effects are highly detrimental from the dual point of view of safety and skiing technique. In addition, they increase the risk of injury.